Understanding and control of interactions between carbon nanotubes and polymers for manufacturing of high-performance composite materials

Composite materials combining carbon nanotubes (CNTs) and polymers have been widely sought to achieve high strength, high toughness, and, in some cases, multifunctional performance. In large part, this is because individual CNTs have outstanding mechanical, electrical and thermal properties; and the nanometer-scale diameter and high aspect ratio enable tailored load transfer to polymers via van der Waals interactions, π interactions, and covalent bonding. While most early research focused on using CNTs as a filler to polymer matrices at low loadings, recent emphasis has been placed on processing methods that leverage organized CNT assembles (e.g., forests, sheets, or fibers). Realization of such composites requires understanding of the how CNT-polymer interactions govern processability and mechanical properties. As such, this review summarizes the fundamental principles that govern CNT-polymer interaction, and how polymer characteristics coupled with CNT network properties influence polymer wetting and infiltration, governing the final composite morphology. Various approaches to infiltration of CNT materials with polymers are explained, in the context of both their governing principles and the overall manufacturing process, and the resulting mechanical properties are discussed. We conclude by highlighting challenges for research and development toward CNT-based structural materials that may find use in future aircraft, spacecraft, and other domains.